The envelope protein of HIV is considered an integral target of AIDS vaccine design. Since this proteins is present on virus particles and infected cells, it is reasonable to predict that immunity raised to env will be a quintessential part of any vaccine, if not essential. A problem with this however, is that different HIV clades have different envelope proteins that can be recognized as different to the immune system. Also, the envelops can exist in different structural forms. The objectives of this contract will be to clone various specific envelope genes of HIV and engineer expression vectors capable of expressing the given envelope proteins in vitro. Next, these envelope proteins will be purified so as to permit their administration to experimental animals to test their immunogenicity. Different forms, monomeric and oligomeric, will be generated and purified. The particular env genes will be identified by the Project Officer.